Computer tape and reel signature for computer data file security

ABSTRACT

Disclosed is a method and apparatus whereby each time a tape is wound upon a prescribed reel, the winding pattern may be assumed to leave the array of tape-edges in a unique &#34;edge profile&#34; represented by the position of each winding edge as viewed from one side of the reel along a radial direction--this &#34;profile&#34; being interpreted as a &#34;winding signature&#34;; the signature may be detected and recorded in a convenient encoded fashion for possible use in uniquely identifying and documenting each unspooling/rewind sequence to thereby monitor tape use. Illustrative tape is shown wound on a conventional reel, as well as means for detecting the &#34;wrap profile&#34; (&#34;edge profile&#34;) of the tape edges on the reel.

BACKGROUND, FEATURES OF INVENTION

This invention relates to means for enhancing the security of tapefiles; and more particularly to methods and associated apparatus fordetecting whether a given reel of tape has been unspooled and rewound.

Workers in the art of making and using spooled webs, such as magnetictape, are, at times, very concerned about security--e.g., about knowingwhether or not a given tape segment has been used during a certain timeperiod. Such problems are extreme in the magnetic tape art where it isbecoming extremely important to be able to detect the use of sensitivetape files. Such files may contain very valuable highly sensitive data(e.g., a "scrambler code" used for transmitting secret, proprietary dataover a relatively non-secure transmission medium).

Thus, many workers in the related arts would be intensely interested inbeing able to detect whether or not a given reel of tape has been"used"; that is, whether the reel has been mounted on a tape drive andthe tape unspooled and operated-upon (e.g., read magnetically and/orwritten-upon, etc.) during a given reference period--e.g., since thereel was last checked by a security officer.

It is also well known that personnel having legitimate access to suchtape files may, at times, be severely tempted to abuse their power anduse tapes illegitimately and in secret--e.g., surreptitiouslywithdrawing a reel of tape and mounting it on a tape drive to run itpast a read-head so as to make a copy-tape of sensitive data thereon.

The subject invention provides a solution, at least in part, to thisproblem and a possible deterrent to such illegitimate use of tapefiles--doing so by teaching formulation of a "reeled-web signature"which can indicate whether a given reel of tape has ever been unspooledand respooled. It goes without saying that workers in the art will findsuch an invention of tremendous value and help.

I have noticed that a typical length of magnetic tape such as "MYLAR"tape segment t shown in FIG. 2 as wound upon an associated tape reel R-1winds upon its reel or spool in a certain "random spooled" fashion. Tapet may be understood as conventional, comprising a magnetic recording webabout one-half inch wide by about 1-5 mils thick and having magneticmaterial recorded on one or both sides of its "MYLAR" (or like)substrate. The tape is typically wrapped upon itself several thousandtimes about the hub of a reel R-1 as is well known in the art. I haveobserved that each time such a length of tape is unwound and thenrewound upon a storage spool, the successive turns, or "reeled layers"of tape virtually never sit in registry exactly atop one another--ratherthey assume a "stacking profile" that is characteristically "random" asis quite schematically indicated in FIGS. 3 and 4.

Such an unspooling and rewinding would typically take place in thecourse of mounting the reel of tape (e.g., supply reel R-2 in FIG. 1) inoperative position on an associated tape drive apparatus TD as wellknown in the art and threading the tape t through a read head apparatusR, and intermediate tape guide means, to terminate on a take-up reelR-1. Thus, as the tape is unspooled from supply reel R-2 and drawn pastthe read head RH and the intermediate guides, it will be understood astaken-up by take-up reel R-1 in a prescribed well known fashion.

While I cannot be sure, I believe that the cause(s) of this "random"stacking profile derive, in part, from such things as the randominfiltration of ambient air between tape turns during wind-up, fromshifting tension forces on the tape during spooling and unspoolingand/or from a shift in winding tension.

Thus, I have formulated a technique for detecting whether a given reelof tape has been unspooled and rewound--even partially--this techniqueinvolving a determination of the reeled-tape "signature" after any, orall, winding sequence, as more particularly described below.

I have, further, devised an improved tape reel wherein a "referencelocus" may be automatically provided in a tape reel for comparison withthe wrapping profile of the tape.

Moreover, the subject invention also teaches techniques and apparatusfor automatically detecting such a wrapping profile or "signature" forany (every) tape-wrapping sequence. That is, each time a segment of tapeis wrapped upon a spool, the wrapping profile may be automaticallydetected and identified uniquely (and preferably encoded) so that eachsuch tape-wrapping sequence can provide a unique "finger-print" ofitself--this preferably being done automatically or semi-automatically.

If such a "signature" be recorded it may be used as a means ofindicating any and all uses of the tape which involve any spooling oftape segment. For instance, a "wind-up log" may be kept for each reel,and dated, so that unauthorized "unspooling and associated use" can beautomatically detected and attended-to--e.g., by a "spot check" of thewind-up log for that reel. Such a practice can obviously be used as apowerful deterrant to any would-be malfactors also!

Thus, it is an object of the subject invention to provide at least someof the foregoing solutions and features of advantage. Another object isto provide a method and means of determining whether a segment of tapehas been unspooled and rewound. A related object is to provide awrapping profile, or "signature" of a "reeled web".

A further object is to provide a determination of the wrapping profilefor a spooled tape. Yet a further object is to detect such a wrappingprofile, or signature, of a spooled tape segment in a prescribed encodedform, convenient for use in improving security against illegitimate tapeusage, etc. A further object is to provide related techniques andapparatus to detect such a signature of reeled web segments. A furtherobject is to provide improved techniques and associated apparatus forspooling tape segments on a prescribed reel. A further related object isto provide prescribed reference loci on such a tape reel for betterdetermining such a "signature".

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will beappreciated by workers as they become better understood by reference tothe following detailed description of present preferred embodiments;these being considered in conjunction with the accompanying drawings,wherein like reference symbols denote like elements:

FIG. 1 is a very schematic idealized frontal showing of salient elementsof a prior art tape drive;

FIG. 2 is a somewhat schematized top view of a typical magnetic tapereel with a segment of tape wrapped thereon in the usual manner andincluding a signature-detector according to one embodiment;

while FIG. 2A is an isometric elevation of a small arcuate section ofthis reel;

and FIG. 3 is a side elevation of this section, with the edges of thetape wound on the reel being emphasized for clarity and viewed inprofile from the side, and enlarged;

while FIG. 4 depicts a representative subsection of the section in FIG.3, being shown in greatly enlarged idealized fashion in conjunction with

FIG. 5 a related "profile scale" indicating relative position of tapewindings; and

FIG. 6 is an end view of a tape reel RR' generally similar to that inFIGS. 2-4, and emphasizing apparatus, according to the invention, forautomatically detecting the wrapping profile of the tape on the reel,with salient functional elements of this detection apparatus embodimentbeing indicated in

FIG. 7 in operative relation with portions of the reel, this beingindicated very schematically in

FIG. 8 in operative relation with a representative, greatly enlarged,subsection of the so-spooled tape, the tape being depicted in thefashion of FIG. 4.

PREFERRED EMBODIMENT; DETERMINATION OF TYPICAL "SIGNATURE" FORREELED-WEB; FIGS. 1-4

As suggested before, FIGS. 2-4 are a schematized, rather idealisticrepresentation of a typical segment of tape t wrapped upon aconventional spool or reel R-1 (tape t, as described above). Thus, FIG.2 will be understood as a somewhat simplified upper isometric of a tapereel R-1 on which segment t of magnetic recording tape will be assumedas conventionally wound. Here, and elsewhere in this disclosure, it maybe assumed that the methods, materials, structure and related techniquesare conventional as practiced in the art today, except as otherwisespecified.

The "slice-of-pie" sectorial section from reel R-1 in FIG. 2A will beunderstood as exploded-away; and as shown rotated 90° in FIG. 3,representing a cross-section of the tape as wound in a given wrappingconfiguration upon the hub of reel R-1. The overlapping layers of tape t(see section at t_(c), FIG. 2A) will be understood as wound inconventional randomly-superposed fashion upon the outer cylindricalperiphery of reel hub RH, the tape spool lying between the sides R_(s),R'_(s) of reel R-1 as is well known in the art.

As an improvement feature of invention (described below), reel R-1 hasbeen indicated as provided with two pairs of reference stubs, orprojections, RR, RR'; one pair RR projecting inwardly from the top andbottom sides R_(s), R'_(s) adjacent the reel hub; and the other pair(RR') adjacent the outer periphery of the sides. The distal faces ofsuch stubs are intended to establish a "reference locus", i.e., planeR_(L) --R_(L) convenient for use in referencing the position of thesuperposed so-wound tape edges as described below.

FIG. 4 is a greatly-enlarged view of a portion of such an edge profilefrom FIG. 3, with each tape edge being given a representative scaler"position-value" relative to such a reference plane R_(L) --R_(L) in thescale of FIG. 5. That is, exemplary layers of tape are given arbitraryscale values in FIG. 5 (adjacent to the illustrative tape segment inFIG. 4) according to the sense (right/left: +, -) and the degree ofvariance of each respective tape-edge from reference plane R_(L)--R_(L).

Now, according to the invention, such an indicated wrapping pattern maybe understood as ordinarily "unique" for each unspooling and rewrappingsequence with the tape segments and their ends falling in differentrespective positions from those of a prior unspooling/rewind sequence.Such a spooling sequence or wrapping signature may, according to theinvention be determined and may be detected; also, where appropriate, itmay be recorded in some appropriate fashion as workers in the art canreadily visualize.

Thus, in FIGS. 3 and 4 successive wrapping layers of tape t on the hubof reel R-1 may be understood as disposed in a conventional "randomlystacked" fashion wherein a profile along either edge of the superposedtape segments may be thought of as a stacking "fingerprint", or"signature", uniquely identifying the manner in which the tape isso-wrapped on reel R-1. Thus, if the referenced stacking plane R_(L)--R_(L) is thought of in terms of a "normal" position along which theedges of the tape segments will fall when they are perfectly unskewedand wrapped to lie in registered superposed fashion,--then one mayarbitrarily assign values to the "deviations" suffered by each layer(loop) of tape, according to the extent it varies from such normalsuperposed registry.

As an example the "profile scale" in FIG. 5 is intended as an exemplaryindication of the relative position of each tape edge te--with selectededges given a scaler value along the assigned positional scale, e.g.,relative to the reference plane R_(L) --R_(L) between the distal facesof stubs RR, RR' as indicated above. Thus, for instance, the distal faceof stub RR has been given a scale value of zero (0) and the tape edgesadjacent thereto have been given values successively of: -5, 8, 0, +2,-3, -7 (with the "minus" values being understood as applying to edgesfalling to one side of the reference plane R_(L) --R_(L) ; and the"plus" values applying to edges falling to the other side of R_(L)--R_(L)). Other values are similarly indicated by way of example, inthis profile scale, as associated with the relative position of otherrepresentative tape edges.

Thus, workers in the art can readily visualize that, using the abovedescribed concept of a wrapping "signature" according to the invention,detection means may be devised (such as a feeler gage type instrument inFIGS. 6-8, described below) which may automatically detect the positionof each successive tape loop edge (e.g., relative to a reference planesuch as R_(L) --R_(L)) and so identify all edge positions. The entirearray of edge-positions may be thus identified as a prescribedwinding-pattern--e.g., in a scalar code of the type suggested in FIG. 5.In this way, detect/encode/indicator means may automatically provide anindication of the "signature", or overall wrapping profile, of theentire spool of tape (for a given winding sequence).

Workers will be quick to appreciate the usefulness of such a "wrappingsignature" concept and will contemplate various ways that it may bedetected and identified and/or recorded. They will also contemplatevarious related techniques for using such a recorded "signature". As oneexample, with such an arrangement according to the invention, a givenset of tapes (tape library) in a certain high-security installationcontaining secret data may be protected by providing"signature-indication" for each reel, every time tape is wound thereon.Then, any unauthorized use of any tape (involving an unspooling/rewindoperation of necessity) may be detected--e.g., in the following manner:

Security PLAN AA

The authorities will provide means, as here taught, for automaticallydetecting the tape wrapping "signature" such as those indicated belowrelative to FIGS. 6-8. They may require that, after each spooling(rewinding) of tape on any reel, the "wrapping signature" be detectedand recorded (preferably automatically or semi-automatically asdescribed below) and provide for any selected encoded representationthereof. Such an encoded "signature" may, for instance, be automaticallyrecorded as data on one, or several, portions of the tape itself (andthese locations and code may be kept secret from the ordinary operatorsif such is desired). They may also require that an encodedrepresentation of the "signature" be automatically printed out andimprinted, in human-readable form, somewhere on (a label) each reel.They may also require that this be recorded elsewhere, such as on amaster file remote from the computer installation and relatively immunefrom tampering by operating personnel.

Moreover, the code itself may of course, be selected of any arbitraryform--and the code may be changed at will in both space and time. Thus,for instance, a first signature code may be recorded on one or severalportions of the tape segment itself; while it may be encoded in adifferent form to be imprinted upon the tape reel and re-encoded in yeta third form for safekeeping at a remote installation. Further, theencoding process may be rendered relatively simple, automatic,inexpensive and convenient as workers in the art well know. Such a codemay be controlled by one, or a very select few, of the securitypersonnel and be changed from time to time at their pleasure.

Workers in the art will readily appreciate that such a system ofautomatic signature detection and encoded recording can be used inseveral ways to discourage, if not completely eliminate, unauthorizeduse of tape files. Each unspooling/spooling operation will generate itsown unique signature (remote from the computer room and inaccessible tothe operators there) which uniquely indicates each and every spoolingoperation. A "spot check" of recorded signatures from time-to-time andunannounced can help greatly to tighten security at such a computerinstallation. During such a spot check the recorded wrapping "signature"can be compared with the actual wrapping profile on any tape reel (e.g.,to detect whether or not the signature recordation system is operativeeach time an actual spooling occurs--and this may be combined with anunspooling/rewinding exercise). Also, the "signature" indicated at thementioned remote installation may then be compared with the actualcondition of selected tape reels--e.g., the monitor agent can, with aseparate "feeler gage" or the like, generate his own signature read-outto see if the actual wrapping profile of selected reels corresponds withthat recorded for them.

Moreover, it will be readily apparent that the very existence of such asecurity system, once properly publicized to the operators at such acomputer installation, should have a very strong deterrent effect--theycan never be sure when a check will be run, and it may reveal that atape file has illegitimately been unspooled and rewound under theirjurisdiction. Workers will readily appreciate how valuable such asecurity system can be and yet how surprisingly simple it is toformulate and implement. As an added fillip, it is even possible toarrange and operate the signature detection instrumentation so as tobaffle the tape operators themselves--that is, they may be allowed towitness an incredibly accurate demonstration of signature-detection, yetwithout being told, or being able to perceive how this is accomplished.(They may be unable to deduce that spooled edge alignment is beingdetected even though they are the ones operating the signature detectionequipment). Obviously, a system which has a degree of mystery and yet"uncanny accuracy" can afford added cautionary value to a securitysystem.

Thus, workers will appreciate that this invention involves noveltechniques for formulating "tape signatures" (e.g., by developingsignature data representing the edge-wrapping pattern of a tape coil)and using them (e.g., by comparing such signature data from time totime).

Exemplary signature detection; FIGS. 6-8

FIGS. 6-8 indicate representative means for detecting a tape wrapping"signature" as above described and contemplated, although workers willrealize that other detection arrangements and techniques may certainlybe used. It will be evident (relative to this and other signaturedetection arrangements) that it is quite simple, convenient andinexpensive to implement signature detection according to thisinvention. Here, and elsewhere, it will be understood that the methods,apparatus materials, etc., will be understood as conventional aspresently known in the art except as otherwise specified.

FIG. 6 will be understood as an idealized end-view of a tape reel R-1'.A length of tape t' will be understood as wrapped in the conventionalmanner on reel R-1' (the tape, reel, etc., of FIGS. 6-8 are to beunderstood as the same as described for FIGS. 1-4 except as otherwisespecified). FIG. 6 may be understood in connection with FIG. 2 wherein aprofile detector means PD, including a manual handle h, is provided,being adapted to be manually drawn along a groove gg cut through a sideRS' of the reel. Thus when such a detector PD is drawn radially acrossthe reel, the individual positions of each successive tape loop orwrapping will be understood as automatically detected andindicated--e.g., in a prescribed selectable code.

More particularly, the functional elements of detector PD are indicatedin FIG. 7 as comprising a mechanical detent or feeler pin, f_(p),mounted to be reciprocated linearly along a given guideway FG, beingurged outwardly therealong by a coil spring sp which is based andoperatively disposed upon the detecting surface of a piezoelectriccrystal PZ. Crystal PZ may be conventionally connected between a sourceof current and an output terminal s_(o) so that, as pin fp is movedtoward and away from the detecting surface of PZ, the pin will causeintermediate bias spring sp to apply greater or lesser pressure to thisdetecting surface. This pressure differential will be understood asconventionally indicated at output s_(o) ; for instance, by an increaseor decrease in read-out voltage as well known in the art. Pin fp will beunderstood as drawn (here, manually, although the drive may be madeautomatic as workers will readily appreciate) along groove gg andarranged to so-engage the edge of each successive wrapped loop of thetape on the reel R-1' as to be shifted in its position toward and awayfrom detector PZ as indicated somewhat schematically in FIG. 8. That is,as the unit PD is drawn, scanningly, across the stacked tape edges, pinfp will be understood as driven, back or forth, against the urging ofspring sp, to exert greater or lesser pressure against transducerPZ--the voltage level output thereof being used to represent theposition of each successive layer as known in the art.

In this manner, as workers will appreciate, an automatic read-out s_(o)may be derived to indicate the wrapping profile. This read-out can bedenominated as the "wrapping fingerprint" or "signature" of thisparticular tape when so-wound upon this reel. Of course, for eachsuccessive wrapping, a different set of fingerprint will presumably begenerated. Moreover, this output may, of course, be readily encoded bymeans well known in the art, e.g., to indicate a profile scale in themanner of the numerical scale indicated in FIG. 5 and described above.

Modify reel with "reference surfaces"

As a preferred embellishment, and to provide a reference fingerprintsignal and a reference position for the tape edges, the pair of likeannular reference rims RR, RR' are provided about the (inner and outer)circumferences of the reel sides and on the inner surfaces thereof, asindicated above relative to FIGS. 3 and 4. The distal faces of theserims are arranged and positioned to protrude from sides R_(s), R_(s) 'sufficient to define a reference plane R_(L) --R_(L) ; this planeintersecting the normal non-skewed position of the wrapped tape edges asfor FIG. 4. In this fashion a referenced read-out can be provided at thebeginning, and at the end, of each sweep of instrument PD across thereel radius--the faces of rims RR, RR' serving as reference surfaces.Pin fp is arranged to brush across these reference surfaces at thebeginning and end of its radial sweep and so provide a "zero reading".In some cases, the detector PD will be arranged to scan either or bothsides of such a reel--and in such a case, such rims RR, RR' will beprovided on both reel sides (as illustrated).

Modifications, alternate embodiments

Workers will contemplate alternate detecting means and other ways ofusing such "signatures" as well as other ways of encoding the"signature".

Conclusion

It will be understood that the preferred embodiments described hereinare only exemplary, and that the invention is capable of manymodifications and variations in construction, arrangement and usewithout departing from the spirit of the concepts taught. As an example,the means and methods disclosed herein are also applicable for certainother uses as workers will contemplate.

All variations of the invention being merely illustrative, the inventionshould be considered as including all possible modifications andvariations coming within the scope of the invention as defined by theappended claims.

What is claimed is:
 1. A method of developing a wrapping profile, orwinding signature, for a tape web segment adapted to be wrapped upon aprescribed reel, this method being adapted to enhance computer tape filesecurity so that each time such a web is wound upon a reel, the windingmode, after repeated windings, is assumed to leave the array of wrappedweb edges in a unique edge wrap profile represented by the position ofeach winding edge as sighted radially along one side of the reel, such aprofile constituting the winding signature, this methodinvolving:providing electronic means for automatically monitoring therelative positions of these web-edges and so detecting this"winding-signature", and also for electronically representing andstoring these position values as a prescribed encoded "signature"representation each time the web is wound; this means being adapted toautomatically make such "signature" representations available for use inmonitoring unspooling and respooling operations.
 2. The method asrecited in claim 1, wherein said representations are arranged to be usedby arranging for the automatic electronic recordation of such edgepositions as encoded signature representations each time a web is sowound; and also providing means to compare such a recordation with apreviously-determined wrapping profile of a subject reel.
 3. The methodas recited in claim 1, wherein such signature representations aregenerated by providing a winding reel with reference surface means andwith edge position detect means which is electronically controlled; saidreference surface means being arranged to establish a reference locusalong which the tape edges will normally lie; and by scanning saiddetect means across said reference surface means and across the edge ofthe so-reeled web whereby to provide a position-value output, indicatingthe variance of tape web winding edges from said reference locus.
 4. Amethod of ascertaining whether a given reel of tape has been unspooledand respooled as a means of enhancing tape file security, this methodcomprising:providing electronic means for automatically detecting thewrapping profile of the tape edges in the form of a prescribed "wrappingsignature"; this "signature" comprising electronic representations ofthe relative positions of said tape edges; and also providing associatedelectronic compare-means for comparing this signature with a knownstandard derived as electronic representations of prior or referencepositions of the edges.
 5. The method as recited in claim 4, involvingestablishing a reference plane using reference surfaces associated withthe tape reel; scanning the wrapped web and detecting the position ofsuccessive loop edges relative to said reference plane; electronicallyassigning values to the deviations of each loop edge relative to saidreference plane.
 6. The method as recited in claim 4, wherein such awrapping profile is automatically detected for each and everytape-spooling sequence by detecting loop-edge position andelectronically encoding the successive position readings to generate aunique "fingerprint" characteristic of each wrapping operation. 7.Apparatus for developing a "stacking fingerprint", or wrap signature, touniquely identify each tape wrapping operation automatically andelectronically on associated tape reel means, this apparatuscomprising:position detect means adapted to be mounted on one side ofsaid tape reel and to be scanned radially across the so-wrapped tape toautomatically detect and indicate the position of each wrapped edge andresponsively generate an output indication thereof; and electronicoutput means adapted to receive and process said indication.
 8. Thecombination as recited in claim 7, as combined with electronic codegenerating means adapted to automatically convert said indication to a"wrapping code" representation.
 9. The combination as recited in claim8, as combined with means for receiving and automatically storing thewrapping code representation each time a tape is spooled, whereby amonitoring sequence is facilitated during which a wrapped tape segmentmay be rescanned to generate a "present wrapping code" representationfor comparison with the so-stored automatic representation of a priorwrapping code, this as a means for checking file security.
 10. Tape reelstorage means including cylindrical reel hub means on which record tapemay be spooled, this hub means including a hollow center portion formounting upon reel rotation means; and a pair of sides mounted on saidhub means and adapted to confine and protect the tape as wrapped; atleast one of said sides being arranged to include reference edge meansadapted to establish a reference-locus against which the wrapped edgeposition of the tape loops may be compared, this side also being adaptedto accommodate automatic electronic signature detect means adapted toscan the coiled edges of said tape to detect the relative positionsthereof.
 11. The apparatus as recited in claim 10, wherein at least oneof said reel sides includes a radial slot adapted to receive said detectmeans, together with a pair of reference surface stubs projected fromsaid reel sides so that their surfaces define said reference-locus. 12.An improved method of winding recording tape on a prescribed spool meansso as to later ascertain whether the tape has been unspooled andrespooled, this method comprising:automatically detecting the wrappingprofile of the tape edges in the form of a prescribed wrapping signatureeach time tape is so spooled; and electronically encoding and storingthis "signature" so as to compare it with a known standard.
 13. Themethod as recited in claim 12, including the step of providing areference wrapping locus and automatically determining the position ofeach wrapped tape edge relative to said locus.
 14. The method as recitedin claim 13, wherein said tape edge positions are automatically detectedand encoded into a chain of edge-position-indicia signals and whereinthose indicia signals are automatically stored as a representation ofthe wrapping signature of the tape each time the tape is spooled. 15.The method as recited in claim 14, wherein, each time said tape isspooled, the wrapping signature signals developed, representing theedge-wrapping pattern of the spooled tape, are stored by electronicstorage means adapted to facilitate electronic comparison of theso-developed signals with a standard pattern representing a prior or anidealized wrapping.
 16. The combination as recited in claim 7, ascombined with said tape reel means on which the tape may be so wrapped,this reel means including reference-surface means, and wherein saiddetect means is disposed and adapted to coact with saidreference-surface means to thereby establish a reference-locus fornormalizing the position values of tape edges.